1. Field of the Invention
The present invention relates to a control circuit for a Christmas light string, and more particularly to a control circuit for controlling the flashing operation of a decorative light string by using three-wire flashing control lamps.
2. Description of the Prior Art
The prior art Christmas light string is formed by a two-wire flashing control lamp 10 electrically connected with a series of regular lamps 11, and an electric plug 2, as shown in FIG. 1. An electric power source is supplied to the Christmas light string via the electric plug 2 and a pair of power lines.
Typically, the prior art two-wire flashing control lamp 10 includes a bimetal plate, a filament, and two conductive poles therein. The conductive poles are connected with exterior conductive wires for facilitating electrical connection to form a decorative light string. The illumination of the light string may be controlled by means of the heating state of the bimetal plate installed in the flashing control lamp.
However, the light string controlled by the prior art flashing control lamp can only create a monotonous flashing effect without various flickering patterns. Even a number of light strings may be electrically connected in parallel. In order to enhance the visible flashing effect of the prior art light string, a known electrical controller by using sequential control technique is widely employed. However, the cost of the controller is rather high.
Accordingly, the primary object of the present invention is to provide an improved control circuit for a decorative light string. The decorative light string of the present invention is provided with at least one three-wire flashing control lamp arranged in the light string, so that versatile flashing effects may be easily achieved. Especially, a number of light strings employing the circuit arrangement of the present invention may be further connected in parallel to present a more versatile sequentially controlling effect.
The other object of the present invention is to provide an improved decorative light string with a simple control circuit arrangement by using three-wire flashing control lamps, without need of electrical controller.
The present invention will be better understood and its numerous objects and advantages will become apparent to those skilled in the art by referencing to the following drawings in which: